


The Knight and the Doctor

by Anchestor



Category: Undertale (Video Game)
Genre: Alternate Universe - Fairy Tale, Curses, Fairy Tale Curses, Fairy Tale Style, Gasterblaster AU, Grillster, Kinda, M/M, Suicide Attempt, Violence
Language: English
Status: Completed
Published: 2018-01-21
Updated: 2018-01-21
Packaged: 2019-03-07 19:16:45
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 10,189
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13441491
Author URL: https://archiveofourown.org/users/Anchestor/pseuds/Anchestor
Summary: Once upon a time, there was a knight made of fire travelling the land. One day he came across a distraught village, and was asked to slay a terrible beast that had been plaguing the land. So he travelled to the Forest of the Forgotten, and found not only the beast with the skull of a dragon, but also a mysterious doctor with a few secrets of his own.Gather round, for this is a tale of bravery, love, and a curse most fowl.





	The Knight and the Doctor

**Author's Note:**

> So while scrolling through Tumblr I saw a post saying something like "Do your stupid Swan Princess AU!" and immediately envisioned Knight!Grillby fighting a big-ass gasterblaster beast thing in a spooky forest like Derek fights Rothbart at the end of the movie and it all spiralled out of control very quickly
> 
> Enjoy!

Once upon a time, there was a handsome knight made of fire travelling the land. He was searching for his luck, an adventure maybe, or perhaps just a nice place to settle down into. One day, he came across a distraught village. Upon seeing his armour and its royal crest, the villagers asked the knight for help. They led him to the village elder. The elder explained their plight: near the village there was a forest, once plentiful. But now, for years a terrible beast had lived there. It had chased all life from the forest. Those who had dared to venture to the beast’s domain had been lucky to escape with their lives, many gravely wounded.

“We dread the day the beast attacks our village”, explained the elder. “Please, noble knight, won’t you free us from this beast that plagues us?”

And the knight, as brave as he was kind of heart, accepted this quest, and set on his journey to the Forest of the Forgotten.

 

Soon the knight arrived to the forest. As he ventured deeper and deeper into the woods, the more ghastly his surroundings grew. Here the trees were gnarly, the branches twisted and bare. The forest was filled with a cool, silvery mist that swallowed all sound, leaving an eerie silence in the air. No birdsong. No wind rustling the trees. Only the crunching of dead leaves under the knight’s feet as he searched his way forward. And soon he began to see signs that he was in the domain of the beast. Some trees had been brought down by a great force; others had large claw marks marking the bark. There was strange charring; unlike any charring the knight had ever seen fire leave. Could a single beast really cause this much destruction? But he bravely ventured forth, until nightfall. He decided to make camp, for even if his own fire would light his way, it made him an easy target in the dark. But then he heard a mighty roar, loud and shrill and ear-shattering, and he knew he had found what he’d been looking for. The knight dashed towards where the sound had come from. 

He came upon a clearing, and laid his eyes on the beast. It was a skeletal creature, no skin, no fur, only bone. And it was gigantic, its maw big enough to swallow a man whole. The claws of the beast were as sharp as sickles, its teeth like daggers. Its form was similar to a dog, but the skull was that of a dragon. It had large eye-sockets that were devoid of light. The beast threw its head back and roared.

It truly was a terrifying sight to behold. But the knight didn’t falter as he drew his sword.

The beast lunged at him, the knight quickly dodged, and swung his sword. But the blade barely nicked the beast’s leg. The creature had already raised its paw to attack, and it’s claws raked deep through the knights’ armour, mauling his chest. He screamed in agony. He tried to step back, away from the beast, but the ground was uneven, riddled with roots, and he faltered. Suddenly the muzzle of the creature was right in front of him, and it sunk its teeth into his arm. The beast lifted the knight from the ground, and shook him by his arm like a rag-doll. It finally threw him against a tree, the impact making the edges of his armour dig into his body painfully. He was dizzy, and every desperate breath of air hurt his chest. Where was his sword? The knight tried to scramble to his feet, but the loose forest ground slid away underneath him, and he fell back down. The beast was in front of him, bright light gathering in its mouth. It opened its maw, and a beam of white fire shot towards him. He didn’t even have time to raise his hands to protect his face. The fire was blinding, all consuming, and so much more forceful than his own flame. The world around him went black.

 

 

When the knight came to, the first thing he became aware of was how soft everything around him felt. Warm. Pleasant. Second he noticed the crackle and hum of a fire that wasn’t his own, the quiet bubbling of a cooking pot, and finally the smell of food. He opened his eyes.

The knight found himself lying in an unfamiliar bed, in an unfamiliar room. He looked around. There were all the things you’d expect to see, such as a table, a drawer and a nightstand with a picture frame on it, which the knight didn’t examine further. But more notably, there were dried herbs and plants hanging from strings in the ceiling, and a large shelf filled with books and bottles and glass jars with various contents. It almost looked like a very cosy witches cottage. Lastly, there was a fireplace with a cooking pot, and a slender figure clad in black robes tending to it.

The knight got up, or at least he tried to. The moment he put weight on his arm a jolt of pain shot through him. It brought up an until now unnoticed pain into his chest too. He groaned. Just the slightest movement, and now his whole body hurt.

“Don’t get up. You’re injured”, a voice said. The voice sounded very strange, but not at all unpleasant. Quite the contrary. The knight turned to look at the stranger by the fireplace: a skeleton monster, who was scooping broth from the pot to a small bowl.

“Here. This will make you feel better”, the stranger continued as he brought the bowl to the knight and helped him drink the broth. The skeleton was right: the knight had barely drunk a few gulps, and the pain was already subsiding to a barely noticeable, dull ache. The broth had a distinct, non-liquorice aftertaste.

The knight sat upright on the bed, and the cover slid off him. His armour and shirt were gone, and his arm and chest had been meticulously wrapped in bandages.

“Where am I?” he asked. The stranger put the bowl away, pulled a chair to the bedside, and sat down.

“You’re still in the Forest of the Forgotten. I found you in the woods this morning, unconscious. So I brought you home, and treated your injuries”, he said.

“Who are you?” the knight asked.

“Doctor W.D. Gaster, at your service”, the stranger answered with a small bow. “And you are one of those foolhardy heroes who come to these woods to fight the beast, I recon?”

“…I am Grillby, knight of the Delta order”, the knight said, miffed. “And trying to free a village of this creature is not foolhardy”, he defended himself.

The doctor looked away.

“I got a good, long look at your wounds, Grillby, knight of the Delta order. You are lucky to have survived until I found you”, he said quietly. “And if I hadn’t, you’d be dead.”

There was a pause. The knight felt a sting of shame. He had been reckless that night, charging blindly at the beast like that. But then he realized something.

“Do you live here? In the forest?” the knight asked. The doctor nodded.

“Then how come the beast hasn’t attacked you? Why would you even life here if it’s so dangerous?” the knight continued.

“The beast is the exact reason why I live here”, the doctor explained. “You see, I’m not only a doctor, but also an alchemist. I put up wards so that the beast can’t escape the forest, to keep the nearby villages safe. But they need to be renewed often.” He sighed. “The beast is trapped here, and so am I.”

The doctor looked at his hands resting on his lap.

“It’s not so bad though. There are plenty of medical herbs for me to research, to keep myself busy. And the beast only comes out at night”, he said. “As long as I stay inside after dark, I’m safe.”

The doctor sighed.

“I know that your mission is noble. And I can see that you are strong. But you should leave the forest before you get yourself killed.”

The knight shook his head.

“I can’t. I made a promise to the villagers. To give up would be as dishonourable as it would be cowardly”, he said firmly.

“I thought you might say something like that”, the doctor said. He sounded… tired. “Then I will at least insist that you wait until the evening before you continue your quest. I want to make sure that you heal properly.”

The knight considered, and nodded. If the beast only came out at night, there would be little to pursue during the day.

 

So the knight and the doctor spent the day together. The knight helped the doctor with the chores of the little hut: they weeded the vegetable garden, stacked firewood, and dried herbs. Though the doctor was adamant on not letting the knight exert himself too much. The two of them talked as they worked: the doctor had many questions about the going-ones of the kingdom and the village, and even more questions about the knight himself, where and how long he had served and such. And the knight told him about his battles past, his adventures, and the doctor listened, enthralled.

And the knight in return asked about the doctor’s life in the forest. The skeleton told him about his research of the healing properties of different plants. The knight didn’t understand all that much of it, but he listened. It was nice to look how the doctor’s eyes lit up with excitement when he talked about the things he had learned, and when he explained his various theories. The doctor was clearly passionate about his trade, and very sharp-witted. And he was kind too, the knight thought, taking a complete stranger to his home, caring for them and treating their injuries. The knight wondered if the doctor was lonely. He had to be, living in the forest all by himself. Such a shame, the knight caught himself thinking. Such a shame that a beautiful treasure like him was hidden away like this. The knight tried to shake those thoughts away, for he was there on a mission. But he couldn’t help but notice just how handsome the doctor was.

 

Eventually the doctor wanted to change the knight’s bandages. He was told to sit on the bed, and the doctor sat next to him. The doctor’s touches were gentle, and the knight nearly shuddered as clever fingers danced along his arm when the doctor poured healing magic upon the wound. The knight looked away, seeking a distraction as the doctor wrapped new gauze around the injured arm. His eyes fell on the picture frame on the nightstand. It was a portrait of the doctor, with two small skeleton children on his lap. The children were grinning, and the doctor was smiling proudly. They all looked happy.

“Are they yours?” the knight asked. The doctor froze.

“What are you talking about?” he asked quietly as he tied the loose ends of the bandage.

“The little skeletons in the picture. They look just like you-”

The doctor reached to the picture frame and quickly turned it facedown.

“I don’t want to talk about it”, he said as he pulled away and wrapped his arms tightly around himself. His eye sockets looked wet.

“Oh, I’m sorry, I shouldn’t have pried, I didn’t mean to upset you-” the knight scrambled.

“It’s fine”, the doctor cut him off. “How does you chest feel? Does anything hurt?”

 

The knight went along with the abrupt change in topic. It turned out that he was healing very well, thanks to the doctor’s skills and magic. When evening came, his injuries were but a scar or two and a bad memory. Remembering that the beast would come out soon, the knight decided to head out. But when he was about to leave, the doctor stopped him.

“Is there anything I can say to make you abandon your quest?” the doctor pleaded quietly. “The beast nearly killed you once. Next time you won’t be so lucky.” The knight shook his head.

“I’m sorry. But, please, don’t worry”, he said. “I’ve learned from my mistakes. I’ll be smarter this time.” The doctor looked at him, as if measuring him, or trying to commit his image to memory. Then he sighed.

“Wait”, he said, and went to rummage through a drawer. When he came back, he pressed a little pouch to the knight’s hand. “Eat this before your battle. It’s something I’ve been saving for a… special occasion.”

“Thank you” the knight said as he examined the pouch: it contained some dried herbs and berries. He put it in his pocket; after all, he had no reason to distrust the handsome, kind doctor who had healed him. The pair said their goodbyes, and the knight was off to find the beast.

 

Darkness fell upon the forest. During his day with the doctor the knight had completely forgotten how quiet and lonesome the woods were. He wandered around aimlessly, until the roar of the beast broke the silence. The knight found the beast in a small valley, but rather than rushing to face the beast, he remained hidden by a cliff and observed it. The beast was fast, and its claws were sharp. He would have to keep his distance. The dry leaves rustling under his feet gave him an idea. He took the pouch the doctor had given to him, and ate its contents. As soon as he had swallowed the last of the herbs, he felt vigorated. As if a strange power was coursing through him, making him stronger, faster. Now was the time to attack.

He gathered flame in his hands, and sent a fast volley of fireballs around the beast, trapping it in a ring of fire as the forest ground caught aflame. The beast spun around in its burning prison, until it saw the knight. He jumped from his high ground, slashing his sword at the growling beast’s right eye. The blade sunk into the bone, and the creature gave a shrill, pained roar. The knight fell to the forest ground, and immediately pressed his hands to the dry leaves, creating a hot wall of flame between himself and the thrashing beast. The top of the beast’s skull was red with marrow, as was the knight’s sword. The beast opened its maw, and shot out a beam of white fire of its own, but the knight dodged. He took a better stance. If only he could blind the creature, so that it wouldn’t be able to attack him. Then he could burn it to death.

He sent three fireballs towards the beast, one right, one left, one at its skull. The beast ducked, and the knight swung his sword at the creature’s left eye. The bloodied blade cut through the beast’s muzzle. It roared in pain, and jumped blindly through the flames, away from the knight, and fled to the forest. The knight gave chase, but he was no match for the speed of the creature, and soon he lost his target to the foreign and dark surroundings of the woods. But the knight searched on, until he simply grew too exhausted to keep going. Sleep claimed him as soon as he made camp.

 

The next morning the knight searched through the forest again. He was hoping to find a trail of marrow, which would lead him to the beast’s daily hiding place. Then he could slay it as it slept. It was a long shot, but it wasn’t like he had anything else to do.

He didn’t find any trace of the beast, but he did notice a dark figure in the mist. He approached quietly. As he got closer he recognized the black-cloaked form of the doctor. He was kneeling on the ground in front of a willow, carefully cutting pieces of bark into a basket with a small knife.

“Good morning, Gaster”, the knight said. He smiled as the doctor jumped a little. Apparently he’d been so focused on his work that he hadn’t heard the knight coming.

“Morning, Grillby”, the doctor said as he turned around. The knight gasped in surprise. The doctor’s head was covered in bandages. The gauze was wrapped from the top of his skull all the way to his mouth. Of the upper half of his face only the eye sockets were visible, as the gauze was fixed around them so that the doctor could see.

“What happened to you!?” asked the knight as he rushed to kneel by the doctor’s side to inspect him closer.

The doctor looked at his hands, as he wrung them in his lap.

“Don’t worry. It was my fault, really. I went to pick moon lilies -they only bloom at night. And I ran into the beast. It was frenzied, and it clawed at me.” He chuckled weakly and rubbed his neck. “You’d think I’d know to stay indoors by now!”

The knight felt angry, at the beast and at himself.

“This is my fault. If I had been able to kill the beast, it wouldn’t have attacked you”, he said, bitter.

“Grillby, please. I knew you’d be fighting the beast tonight, I shouldn’t have gone outside. I’m to blame”, the doctor placated.

The knight took to doctor’s hands in his own, and looked him in the eyes.

“Tonight. Tonight I’ll slay the beast for sure. It won’t hurt you ever again”, he promised. The doctor gave a weak smile.

“I know you will.” he said quietly.

“So! Since you are here, would you care to join me for lunch? I’m making quiche”, the doctor said abruptly as he stood up and grabbed his basket. The knight smiled.

“I’d love to.”

 

So the pair went to the doctor’s cabin and ate. The crust was burnt around the edges, but otherwise the quiche was pretty good. The doctor once again proved himself to be pleasant company, and the knight felt reluctant to leave. So he asked if there were any chores he could help with.

“It’s the least I can do to repay your kindness”, he explained. The doctor tasked him with chopping wood while he stacked the logs. The two of them talked about everything between the sky and the earth as they worked. The knight toiled away, and the hot midday sun made him take his shirt off.

Suddenly there was a clatter of wood. He turned to look: the doctor had accidentally knocked over a stack of firewood, and now he was staring at the knight. A blush was visible from underneath the bandages.

“What?” the knight asked.

“Oh nothing I was just admiring your phys- _technique!_ Yes! You handle that axe very well!” the doctor scrambled, blush darkening.

“You know what I should go draw some water from the well I’ll be right back bye!” he continued as he fled behind the woodshed. The knight chuckled, grinning to himself. He wouldn’t mind at all if the doctor liked what he saw. Besides, the doctor was cute when he was flustered.

As the day went on the knight thought about the doctor. He couldn’t quite pin why, but being beside the other made him happy, and he felt a sense of belonging when they were together. He wanted to stay with the doctor, forever if he would have him. The knight’s heart was filled with longing; it almost felt like an oddly pleasant ache. Whenever they touched, be it an accidental, passing brush or a gripped hand, the knight could see a hint of a blush, or maybe a smile. This led the knight to hope that the doctor felt the same as he did.

 

The knight offered to make dinner for them, and the doctor accepted.

“You know”, the knight said as they ate, “I’ve been thinking about opening a tavern once this is all over. You should come visit me sometime.” As he spoke he reached for the doctors hand on the table, and touched his phalanges meaningfully. “Since you wont be stuck in the forest anymore.”

The doctor laced they fingers together.

“That sounds nice. I’d love to come”, the doctor said. He sounded wistful.

 

As they got stood from the table, the knight accidentally bumped into the nightstand, and the picture frame fell over. Luckily the doctor caught it, so it didn’t break.

“Oh no, I’m sorry”, the knight apologized.

“It’s alright”, the doctor said, looking at the picture in his hands. He sat on the bed.

“You were right, by the way”, he said. The knight tilted his head in question.

“I never answered you question yesterday. Yes, they are mine”, the doctor explained. He gestured to the knight to come sit beside him on the bed, so he did.

“This is Sans-,” the doctor pointed to one of the children in the picture, “-and this is Papyrus. My clever little boys.” He had a sad smile on his face.

“Sans is such a jester. He likes pranks and puns and bad jokes. He’s a bit lazy, but incredibly smart. Papyrus on the other hand is a bundle of energy, always running around, trying to make friends. Keeping his brother on the straight and narrow.”

“Do they live in the village?” the knight asked. The doctor nodded. His eyes were fixed on the picture.

“When the beast began to plague the land, I had to do something. I knew I could trap it with wards, and keep my sons safe. …But the forest is no place for children.” The doctor hugged the picture frame tightly.

“So I left them at an orphanage. It’s run by an old friend, she said she’d look after them. I told them-” he swallowed hard. “I told them that I had to go away for a while. That I had something important to do. That I’d be back as soon as I could.” Fat tears began to roll down his face. “That was years ago.” His voice broke. The knight pulled the doctor into a warm embrace, and held him as he wept.

“I miss them. God, I miss them _so much-_ ” the doctor sobbed. The knight rubbed soothing circles into the doctor’s back, and let the other cry himself out.

Eventually the doctor pulled away, wiping the last of his tears on his sleeve.

“I’m sorry. I didn’t mean to get all weepy on you”, he sniffled.

“It’s okay”, the knight said softly.

“Uh, dammit. My bandages-” the doctor complained. The gauze under his eye sockets had gotten wet, and the wrapping had gotten loose. The doctor gripped his face before the bandages fell apart.

“I should change these- Grillby, could you please get something for me?” he asked.

“Of course. What do you need?” the knight answered.

“Broadleaf plantain. There’s a good spot on a hill north from here. It’s not terribly far”, the doctor explained.

So the knight set out to find some.

 

He had barely stepped out of the cabin when he remembered that he had seen the plant before. There was a grassy patch full of them just behind the woodshed. Maybe the doctor had forgotten the plant grew so near? If there were something wrong with the ones growing there, it wouldn’t be too much time wasted before going to the hill, the knight thought as he picked a bundle of leaves and pocketed them. And if the other truly had just forgotten, the knight could be back to his dear doctor that much sooner.

So the knight returned to the cabin, pleased with how fast he had been. He barely noticed how the evening sun dyed the clouds a lovely shade of pink.

“Gaster, would these do-?” he began, but abruptly halted. The doctor was still sitting on the bed, and he had completely unwrapped his skull. His face was marred with two large scars, one from his right eye to the top of his head, one from his left eye to his mouth.

Scars identical to the ones the knight had given the beast.

“Grillby! You’re back already, how’d you-” the doctor scrambled as he tried to cover his face with his hands.

“Your scars- they’re just like- the beast’s? But… How-?” the knight shambled over the words. His mind was racing. It couldn’t be just a coincidence. But any other option was just as impossible.

The doctor rushed up and pushed the knight aside as he escaped through the door. Shaken from his stupor, the knight quickly followed the other outside.

 

The doctor stood in front of the cottage, frozen. Staring as the last rays of sun disappeared beyond the horizon.

“I suppose that’s it, then”, the doctor whispered in a shaky voice. “You always were a fool, weren’t you, Gaster? Greedy and selfish. Always wanting more than you’re allowed to have.” He turned to look at the knight. Dark mist had started to appear around the doctor’s feet; it’s inky tendrils slowly climbing up.

“I should have made you leave the moment you woke up.” The doctor wrapped his arms around himself tightly. “But it was just so nice to have someone to talk to, you know? And then for that someone to be someone like you-” he choked. The cloud of mist was covering him to his waist. The knight took a step toward the skeleton-

“NO! Stay back!” the doctor threw his hand forward, and with a _ting!_ the knights Soul turned blue, and he was shoved against the wall of the cottage.

“Gaster-” he begun.

“Grillby, _please._ I don’t want to hurt you”, the doctor pleaded. “Like I always hurt the ones I care about.” The dark mist was at his shoulders, covering his hands, and the blue hold started to falter.

“Run, Grillby. I beg of you. Just run-!” the doctor gasped as the mist swallowed him completely. The hold on the knight’s Soul broke, but he could only stand there, frozen, as he watched in horror. The cloud was still growing, rapidly, black tendrils churning in the dying light; the only sign of the doctor the hoarse screaming emanating from the heart of the mist. The billow swelled until it was gigantic, and the screams grew into a roar, loud and shrill and ear-shattering. The mist vanished, as if collapsing in on itself, and the knight was face-to-face with the beast, two large cracks marring its skull.

 

By pure instinct, the knight drew his sword. The beast leapt at him, swiping its claws, and the knight barely managed to dodge. He was about to swing his blade- but. The beast and the doctor were one and the same. Whatever attack the knight laid on the beast, the doctor would receive. He’d already seen the scars on the other’s skull, scars _he_ had carved.

He could not hurt the doctor like that again. He could not fight the beast.

The knight sheathed his sword and ran, hiding behind some trees, just far enough that the beast couldn’t find him. But still close enough not to lose sight of the beast. The creature roared, spat fire from its maw and downed trees with its paws in search of its escaped prey. Eventually it lost interest, and ran deeper into the forest. The knight followed it, this task much easier now that the beast wasn’t frenzied by fresh wounds. Through the night he followed the beast as it wreaked havoc upon the forest, clawing at trees and itself. Shortly before sunrise, the beast slowed down, its canter growing sluggish until it dragged its feet across the forest ground, finally slumping on the dead leaves. The dark mist was once again gathering around the beast, covering it completely. The cloud shrank, as if the mist was being chased away by the first rays of daybreak. And when the sun was just barely visible in the horizon, all that was left was the doctor’s slender form, lying on the cold ground, unconscious.

Like a puppet with the strings cut.

The knight approached, carefully, quietly. The skeleton looked so very frail.

He gently lifted the doctor’s limp body in his arms, cradling him to his chest. And he began his trek back to the cottage. When he got there, he laid the doctor on the bed and tucked him in. Then he sat on the chair, waiting for the doctor to wake up.

 

When the knight woke up, it was well into the afternoon. When had he dozed off?

He heard the rustle of fabric as the skeleton stirred in bed. The doctor was slowly blinking his eye sockets open. Then he sat up, and looked around, disoriented. He saw the knight. Realisation dawned on his face. Then sadness. The doctor leaned his back against the wall, and pulled his legs towards his chest, hugging them.

“Did I hurt you?” the doctor asked quietly. The knight shook his head.

“Thank God for small mercies”, the doctor muttered as he buried his skull in his knees.

The silence hung in the air, thick and heavy.

“You are the beast”, the knight stated. The doctor didn’t answer. He didn’t have to.

“How?”

The doctor took a deep breath. He looked to the side, where the picture frame stood.

“Sans was always a child of poor health. He was weak and sickly since birth. Every morning I went to get him, I feared I’d only find dust in the crib. There was little improvement as he grew. I- I just wanted him to be able to have a normal childhood, to run and jump and climb trees without having to fear the worst every time he stumbled.” The doctor turned to stare in front of himself, without really seeing anything.

“So I began to research what I could. Old ways of healing. Alchemy. And my research led me down a dark path. I saw things, dreadful, magnificent things. Things never meant for mortals to stir. And then it all went to hell.” He hugged himself tighter.

“This curse is the punishment for my hubris. So now, when the sun sets and the world grows dark, darker, yet darker, I become this… _creature._ A mindless beast of rage and destruction.” His voice was laced with loathing. But it was quickly replaced with sorrow: “I knew that I wasn’t safe. And if my children ever got hurt by my own hand- I’d never be able to live with that. So I banished myself to the Forest of the Forgotten.”

He sighed. “I thought here I wouldn’t be able to hurt anyone. I guess I didn’t take into account foolhardy heroes like you.” The doctor gave a hollow laugh.

“Is there any way to break this curse?” the knight asked urgently. The doctor gave him a look.

“You think I haven’t tried? I’ve read every book, tried every potion, every spell, everything I could think of. Nothing. There is no way.” He hung his head. “Only death can release me.”

“No. There has to be a way for me to help you”, the knight said firmly. The doctor looked at him, as if measuring him.

“Do you truly wish to help me?” he asked quietly.

“Yes”, the knight answered without hesitation. The doctor uncurled from the ball he had pulled himself into, and sat up straight. He closed his eyes.

“Then you will pull out your sword and finish your mission. I am the beast you promised to slay, after all.” His voice was toneless, and his position open, only the dark fabric of his robe shielding him.

“No. No!” the knight shouted as he rushed to embrace the doctor.

“Can’t you see how much I care about you? I could never hurt you, let alone-!”

“But I hurt you”, the doctor interrupted, his voice hollow. “I nearly killed you. And there will come a time when it won’t be ‘nearly’. Please, Grillby.” He continued softly. “I don’t want to keep living like this. Hiding alone in a forest, never able to become attached because I will hurt them, waking up in the morning with blood on my hands without knowing why.”

The knight trembled. He pulled away. It felt like something inside him was breaking into a thousand icy shards.

“If that is what you want”, he said shakily.

“Thank you”, the doctor whispered.

“But I came to this forest to slay a beast, not to murder an innocent. I’ll… do it tonight. Then it won’t be you, not directly at least.” The knight said.

“If that is what you wish”, the doctor answered.

The air was once again filled with silence. There was so much the knight wanted to say, and he would now never get the chance to.

“I should go. Prepare.” He finally said. The doctor nodded.

As the knight turned to leave, the doctor said: “Wait!” and went to take something from a drawer. It was an old letter.

“Could you please deliver this… afterwards? It’s for my children”, he explained.

The knight nodded and took the letter. They said their goodbyes, and the knight went, leaving the doctor alone in the cabin.

The doctor hugged himself and took a shaky breath.

“I don’t want to die”, he whispered to the empty room.

 

The wind blew lone and mournful as the knight sat on a log, waiting. He picked up leaves, one by one, and let them slowly burn in his hands.

The light was dying fast.

He heard the roar of the beast.

The knight was quick to rush towards the sound, and soon he saw the beast. He fanned his flame bright, standing like a beacon in the dark forest.

“Hey! Over here!” he shouted, and launched a fireball at the beast. It sidestepped the attack, locked its empty eye sockets on the knight, and lunged at him. But the knight had already started running. The creature gave chase.

The knight ran through the woods, the heavy stamping of the beast at his heels. He could almost feel the fiery breath at his neck; hear the growl by his ear. He ran.

There was a canopy of trees ahead, branches arching overhead, creating something like a hallway with a steep cliff on both sides. The knight ran through, and the beast followed. Just as he was almost through, he pulled his sword- and cut a wire near the ground. Heavy ropes fell from the trees, trapping the beast in a tight net, pinning it to the ground. It roared, enraged. It threw its body as much as it could, trying to escape its bindings. But the struggle was in vain: the rope was where its claws could not reach, and where it couldn’t turn its head to bite the trap apart. In blind anger it spat white fire from its maw where it could.

The knight stood and watched the beast tire itself out. Eventually it slumped on the ground, too exhausted to fight anymore.

It didn’t even growl at the knight as he approached. He still had the blade in his hand. With slow steps he neared the beast’s skull, its neck. He could feel the creature’s eyes following him. The knight tried to just focus on the thick vertebrae that connected the beast’s head to its body.

He raised his sword, high, like the axe of an executioner.

He stood perfectly still.

The sword slipped away from his fingers, and dropped to the ground with a clang as the knight fell to his knees and cried. Hot, molten tears ran down his face as he wailed into the night.

“I can’t”, he said, turning to look at the eyes of the beast. “I’m sorry, but I _can’t._ ” The knight wiped his eyes, or at least tried to, as he moved towards the beast’s skull, and embraced it. The creature remained still.

“I’m sorry”, he whispered.

“I love you.” He pressed a kiss on the forehead of the beast.

**Interesting.**

 

The knight scrambled up, startled, grabbing his sword. What was that voice? Where had it come from? He took a defensive stance in front of the tied up beast.

“Who’s there!?” he demanded.

**Now _that_ is a question someone wise would call _wrongly asked_.**

The knight looked around, but he didn’t see anyone. There were only the trees all around him, the flicker of his own flame the only thing illuminating the forest. He fanned his flame higher, brighter. But the darkness seemed to swallow his light completely.

He tightened his grip on his sword. The shadows were… wrong, somehow. Alive.

Wicked.

“What would be the right question, then?” the knight asked, trying to keep his voice steady. He didn’t know what was going on, but he knew he didn’t like it.

The voice laughed, a sound as unnerving as it was unnatural. It sounded like it was coming from everywhere at once.

“…what are you?” the knight continued, taking a few steps forward, turning around. Where was this thing?

**There you go. Not _completely_ daft, are you now?**

Suddenly the air felt cold, suffocatingly so.

**I am what was and what once again will be. I am what lies beyond your world, and others like it. I am older than time and grander than space. I am the Void.**

The beast growled.

**Oh hush you.**

A tendril of dark mist appeared in the air, right in front of the beast’s snout. It tried to scramble away from the mist, but the rope held tight. The dark cloud disappeared as the beast had no choice but to breathe it in. As soon as it was all gone, the creature slumped limply on the ground, eyes shut.

“Gaster-!” the knight shouted, panicked, as he rushed back to the side of the beast.

**You silly thing. He couldn’t hear you even if I’d let him stay awake. His mind is completely gone when he is like this. You _do_ know that, right?**

The voice bubbled, in a mocking imitation of a giggle.

**And that makes me rather curious about your little love declaration at my wonderful beastie over there. Too much of a coward to tell him when he could reject you?**

“ _Your_ beast?” the knight asked, ignoring the insult.

**Quite. I gave your darling doctor the curse that binds him. He was getting annoying. The foolish creature was ready to bend the laws of this world off their rails in his selfishness. He searched for power. What he found was _me_.**

“You gave him the curse!?” the knight asked, hope rising. “Then you can lift it!”

**Now why would I do that? The meddling little cretin deserves his curse. Besides, it’s just so… _fun_ to watch the pathetic thing tear himself apart.**

“Don’t talk about him like that-!” the knight snarled.

**Or what?**

Suddenly a block of ice appeared on the tip of the knight’s sword, the ice growing, creeping fast across the blade, towards the hilt. The knight dropped his frozen weapon with a shout, just before the ice could reach his flaming fingers. As it hit the ground, the sword shattered into a shower of razor-sharp pieces.

**You mortals think you’re meaningless little lives are _so important_. Self-centred, arrogant, greedy creatures, you are. Kicking and screaming and killing just to live long enough to breed. It’s _disgusting_. At least it’s amusing to watch sometimes. Oh, what sweet irony it had been if you had killed him, or he you! Two Souls, destined for each other, only for one to strike the other down.**

The voice paused.

**I will admit though: watching the skeleton languish has grown old. Perhaps…**

The voice giggled again.

**Oh yes. It’s your lucky day, my little tin soldier. I’ll make a deal with you: if you can pass three trials I give you, I’ll lift the curse, and the doctor is yours to do with as you please. But. You have to finish them all tonight. And if you fail, he remains a beast forever. Now doesn’t _that_ sound interesting?**

The knight hesitated. He wasn’t afraid of the trials: he’d do anything for the doctor. But with such a great risk to the other, this was hardly his decision to make alone.

Apparently, he’d waited too long to answer.

**You know, if you are going to be _boring_ about this, I can just kill both of you now and be done with it.**

Needle-sharp icicles appeared in the air, flying towards the knight and the beast like arrows.

“Wait! I’ll do it!” the knight shouted, raising his hands for protection. The icicles stopped mid-air, just a breath away from the two of them.

**_Excellent choice._ **

 

The ground disappeared under the knight’s feet, and he fell through darkness. He landed on his back as he hit the ground. When he got up, he didn’t recognize where he was. It still looked like the forest, but he was by a foreign lake, the water quietly lapping at the rocky shore. By the treeline, quite a bit away from the lake, there was a stone pedestal, and on top of the pedestal stood a black chalice.

**For your first task, you have to fill that chalice with water from the lake. Oh, don’t worry; I’ll give you something to carry the water with. In fact, _make sure_ to carry every drop in _this_.**

There was a clang of something metallic dropping behind the knight. When he turned to look, he saw a sieve on the stone ground.

**Remember. Every drop, in that.**

And the knight could feel that he was alone.

He went to examine the chalice. It was firmly attached to the pedestal. He then went to the shore, picking up the sieve on the way.

He submerged the sieve in the lake, careful not to let the water touch his fiery hand. As he lifted the sieve, the water poured away. Perhaps if he was fast enough, some water would remain in the sieve? He filled it again, and began running. But the water ran from the sieve again, and once he reached the chalice, not even a drop remained.

He returned to the lakeside and sat on the rocky ground. How could he fill the chalice if the water ran from the holes of the sieve?

He felt a lump pressing against himself from his pocket. He dug out his pocket’s contents: It was a crumpled handful of round, green leaves. The plantain the doctor had asked him to get.

The knight looked at the plant. He now understood that getting the leaves was just a fool’s errand to get rid of him, so that the doctor could change his bandages alone. Hide his scars. If the knight had taken too long, he would have been none the wiser about the doctor’s curse. He might have killed the beast that night.

The knight watched as dead leaves floated on the surface of the lake. He had been so pleased with himself when he got the plants, thinking he could help mend the doctor’s wounds…

He blinked. He looked at the large leaves in his hand. The holes of the sieve weren’t wounds, but…

He took the sieve, and lined its insides with the leaves. Then he filled the sieve in the lake. The leave coating wasn’t waterproof, but the flow was much lesser than it used to be. The knight rushed to the chalice, and poured the water from the sieve to it. Not much water had remained after the journey, but the chalice was now half-full. Another trip to the lakeside, and the knight had filled the chalice.

“I’m done. I did it. It’s full”, he said.

 

The air grew cold again.

**Oh. So you have. Well then.**

The knight heard a rustle behind him. As he turned, he saw a waist-high heap. When he walked closer, he saw what the pile was made out of: it was a mixture of grain and small gravel.

**For your next trial, separate the pile. Not a single grain is to be found among the gravel.**

**Remember. You have until dawn.**

And the presence disappeared.

The knight kneeled in front of the heap, and began to sort it into two small piles. He worked for an hour, picking the grain and gravel apart one by one. Then two hours. When he looked up, he saw he had barely made a dent to the heap. At this rate, it would take days to sort it, and he didn’t even have a single full night.

He looked at the mixed kernels in his palm, then balled his hand into a fist in anger. He hadn’t expected the trials to be anything but difficult, but this was impossible. Now he was going to lose the one he cared so much for just because he wasn’t fast enough. This wasn’t fair-!

A sizzling, churning sound came from his hand, and a wisp of smoke escaped from between his fingers. He opened his palm, confused. What he found was pieces of soot stained gravel, and a bit of ash. His anger had fanned his flame high enough to burn the grain.

Hope rose within the knight as he sunk his hands into the pile. He pushed his hottest fire through his hands, setting the pile ablaze. Soon a small mount of ash and gravel was left. He grabbed the sieve off the ground where he had dropped it, and cleaned the leaves out. He guided heat into it, and it dried with a quick, steamy hiss. Then he scooped handfuls the mixed ash and gravel into the sieve, and shook it until all the ash had fallen out, only gravel clinking inside. He poured the gravel into it’s own pile, and began from the start, again and again until he had worked through the entire heap.

“I’m done. I did it. It’s separated!” he said.

 

**Did you? I can see the gravel. But where is the grain?**

“Right there.” The knight pointed at the ash pile.

**That is not grain.**

“You only said that I had to separate the pile. You didn’t say that the grain couldn’t be burned. And there isn’t a single grain among the gravel. Just like you told me to do”, the knight replied.

There was a pause.

**Oh. Well, aren’t you just _clever_. Clever, _clever_ little tin soldier. You know what? For being so clever, I think I’ll give you a little gift.**

A cloud of dark mist appeared in the air, in front of the knight, just a little above his head.

**Try not to lose it, you’ll need it later.**

From the cloud dropped the slender figure of the doctor, and he fell unceremoniously to the ground.

“Gaster!” the knight cried out as he rushed to the skeleton’s side. He gathered the limp body in his arms. The others eye sockets were closed, but he was breathing evenly.

“Gaster, wake up!” the knight pleaded with a desperate voice.

**Stop wasting your breath. He’ll sleep until he’s needed. But now. Your final trial.**

The ground melted away from underneath the knight, and he fell through darkness once again, clutching the skeleton to his chest.

 

He landed on a hard wooden floor. The knight looked around: the walls of the room were lined with tools, there was an anvil and a glowing furnace. He was in a forge.

**Do you know why I cursed your dear little doctor?**

The knight bit his tongue, thinking it wiser not to insult the being that still held so much power over the two of them.

**It was a way to contain him. As he was, he could have torn the world apart if allowed to continue on his path. But with the curse… I knew he would isolate himself to protect his fletchlings. And isolated he would not have what he would need. His anguish taking even his will to continue was just the cherry on top.**

**So. Even if I am to lift the curse, he must remain restrained. Your final trial is to bind him. Craft him a chain. Once he is fettered, I’ll lift his curse.**

“I have to shackle him?” the knight asked.

**You could sound a little more excited. The way he is now he’s useless to you. If you pass this final trial, he’ll fit in your bed for the night. Isn’t that what you wanted?**

“Shut up!” the knight growled. The voice laughed.

**Now then. The chain you’ll forge must be unbreakable and irremovable, by force or by magic. For what’s the point if you can just take them off once the curse is lifted? And just to keep things interesting…**

There was a flash of darkness, and the knight felt a sting in his throat, and his tongue stuck to the roof of his mouth. His hands flew to his throat.

“What did you do to me!?” he shouted, or tried to. But when he opened his mouth, not a sound came out.

**What fun is it if you just _explain_ why you need to chain him? Don’t worry; your tongue will be unlocked once he is bound.**

**You better get to work, my _clever_ little tin soldier. I am curious what you’ll do.**

And the presence was gone.

The knight and the unconscious doctor were alone.

 

The knight felt shaken. He gathered the doctor’s limp body in his arms, and laid him on a bench, so that the other may sleep at least a little comfortably. He then tried to speak again, but no matter how he tried, he couldn’t make a sound. He considered what he was tasked.

He doubted that he could explain the situation to the doctor without speaking. He’d have to overpower the skeleton and chain him by force, and pray the doctor would forgive him afterwards. Just the though of assaulting the doctor like that made him shudder with self-loathing. And just to even get there, he would have to forge a good enough manacle.

The knight got to work. The forge was hot, and the metal yielded easily under his tools. He soon had made a single, thick link. To test it, he placed it on the anvil, and hit it with a sledgehammer. It bent and tore, leaving a mangled piece of iron behind. He shook his head. If a single hit was enough to break this one link, a shackle made from ones like it would not be unbreakable.

He tried to forge another link, and then another. Different metal alloys, different structures, different thicknesses. They all broke.

The knight felt hopeless. He might have everything he needed to make an ordinary shackle in the forge, but he knew that crafting a full chain took even the most skilled of blacksmiths’ days. And he only had the rest of the night, and knew barely enough about the trade to maintain his armour. And all that would be just to make an ordinary shackle. Something unbreakable would have to be crafted by magic that he simply didn’t possess.

This wasn’t like the other trials where he could just force his way through. He simply didn’t know what to do.

He sat on the bench. The knight felt utterly exhausted. He hadn’t slept all night. He had fought so hard to break the curse, and now, when he was so close to succeeding, victory nearly at his fingertips- he couldn’t do it.

He looked at the slumbering doctor, tears pricking behind his eyes, spilling over.

_I just wanted to be with you_ , he wanted to tell the doctor. _I just wanted to help you, to free you, to stay with you and make you happy. I could have built us a home. You and me and your children, we all could have lived there, together. I might not have any riches or finery, but what I have we could have shared. I could have taken care of you when you got sick. I just wanted to be with you, through better and worse._

An idea arose. A mad idea, a desperate idea. But the grain burnt to ashes had been accepted, hadn’t it? Then again, it hadn’t been the difference between loss and success. The knight stood up. It was a long shot. But it was the only one he had.

He picked up a small piece of metal, the tools he needed, and, for the last time, got to work.

 

Soon he was finished. He went to the doctor, and shook his shoulder gently. The voice had said that the doctor would wake up once he was needed.

The skeleton blinked his eye sockets open.

He sat up, slowly, and looked around himself, sleepiness giving away to confusion.

“Grillby? Where are we?” he asked slowly.

The knight opened his mouth, but no sound came out. He gestured to his throat, and shook his head.

“…You can’t talk? Wh- what happened to you? Are you alright!?” the doctor asked urgently.

The knight nodded, waiving his hand dismissively.

“I- uh. Alright. Do you know what’s going on?”

The knight nodded firmly.

“O-Okay then. I trust you’ll explain all this once you can”, the doctor said. “Do you know what, uh, happens next?”

The knight did.

He got down on one knee, and revealed two small iron rings on his palm.

“Uhh. What?” The doctor’s brow furrowed in confusion. The knight put one of the rings aside, took the skeleton’s left hand, and brought the other ring close, letting it hover right in front of the tip of the doctors ring finger. Then he looked the skeleton in the eyes, a question written upon the knight’s face. The doctor’s eye sockets went wide with realisation.

“You- you’re asking me to… God, I-”

But the doctor’s words were interrupted as the knight cupped his face, leaned forward and kissed him.

Soft, at first, then more passionate, as he tried to pour all his love, all his promises, all that he wanted to say but couldn’t into the kiss.

And when they parted, he felt absolutely breathless. He opened his eyes, and saw his own expression mirrored on the doctor’s face.

“Yes”, came the answer, quietly. The skeleton opened his eyes.

“I’ll marry you”, he said more firmly, and grabbed the knight by his collar, pulling him into a second kiss. The world forgotten, the knight’s Soul soared with joy. He fumbled as he slipped the ring on the doctor’s finger, and the doctor put the other ring on the knight. The doctor laughed, a giddy, excited laugh, and they embraced.

**What is the meaning of this?**

 

The doctor froze. The light in his eye sockets disappeared.

“ _You_ ”, he said with a shaky voice, out of anger or fear, the knight couldn’t tell. He held the other tighter.

A jolt of pain stabbed the knight’s throat. “Ah!” he gasped.

**Elemental. Explain yourself.**

The knight breathed in deep breaths.

“Marrying someone is a vow. A contract. A _bind_.” The knight began. “’The old ball and chain’, that’s what they call it, don’t they? And since it’s a promise. It’s not something that can be broken by force.”

There was a stunned silence. Then the voice began to laugh, a loud, maniacal laugh. The room around the knight and the doctor shook, the walls bending, and everything around them shattered into splinters. The floor gone, they fell through darkness, clinging to each other tightly.

They landed on the ground, the misty woods around them familiar.

**You dirty little cheater.**

“We played by all the same rules”, the knight answered, defiant. “And I won. Now hold your end of the bargain and lift the curse!”

**You are a courageous one, I’ll give you that, elemental. Or perhaps just very foolish.**

Suddenly the doctor convulsed, and he threw his head back with a short-lived scream, his face twisting into a pained expression. Dark mist poured out of his mouth, dissipating in the air. As the last of the mist was gone, his relief took place upon his features, and he fell limp, panting hard.

**Remember, alchemist. If you ever cross me again, I won’t be this merciful.**

Rays of light were peaking across the horizon, and the presence disappeared with the darkness.

The knight held the doctor tight as the skeleton regained his bearings, blinking his eye sockets in the growing light. The sun coloured the sky in a rosy colour, lighting the clouds ablaze like glowing embers.

“It’s the sunrise, Grillby”, the doctor said quietly. “God, I can’t even remember the last time I saw a sunrise.”

 

 

The knight and the doctor walked hand in hand through the village. After watching the sunrise, the knight had recounted the tale of his trials to break the curse to the doctor. Then the doctor had hastily grabbed a bag full of his most essential belongings from the hut, and the two of them had begun their trek away from the forest. When they arrived to the village, the knight had soon been surrounded by people asking about his quest. The knight had told them that the beast would trouble them no longer. The word had spread quickly, as the villagers rejoiced.

“Grillby?”

The knight was awakened from his musings. He turned his attention to the doctor. The skeleton pulled his hand from the knight’s, and fidgeted with the ring on his finger.

“So, I know that you proposing was part of the trials. And I’m not sure if we can get a proper divorce without causing the curse to return or something. But… just because we are technically married doesn’t mean we have to stay together. I just- I know you were under a lot of duress. So. I’m thankful for all that you did for me. But I’m not going to make you stay with me just because the whole marriage thing was the only loophole you could think of”, the doctor said, his voice unsure.

“Gaster.” The knight wrapped his hands around the doctor’s. “I would have asked you to marry me, curse or no curse. Okay, alright, I would have given it _a little_ more time, but I would have asked.”

The doctor smiled, and laced their fingers together. They continued their walk through the village.

The pair soon arrived at a large house. Two skeleton children were playing in front of the building.

 

The doctor stopped.

One of the children noticed them, scrambled to his feet, and began running towards to doctor.

“DADDY!”

The doctor dropped down, and caught the running child in his arms.

“DADDY, YOU’RE BACK! SANS, SANS I TOLD YOU HE’D BE BACK REALLY SOON, I TOLD YOU!” the child exclaimed as the doctor hugged him tightly.

“My little Papyrus-!” the doctor said shakily as he nuzzled the boy. “And Sans-”

The other child had walked up to them, but not too close. He was standing there, hands balled into little fists, wetness at the corners of his eye sockets.

“Sans?”

“you were gone. a _really_ long time.” the child accused. He closed his eyes, and fat tears rolled down his cheeks. “are you gonna leave again?”

“Sans, no. Never again! I promise”, the doctor answered as he set the child in his arms down and rushed to hug the other.

The child gripped the doctor’s robe, burying his face in it.

“i missed you”, he said, voice muffled by the fabric.

“I missed you, too. So, so much”, the doctor answered, his voice breaking.

“But I’m back, see? We’re all together again. No tears now, okay?” he continued, wiping his own eyes on his sleeve.

“okay.”

“Now then, have you two been good boys while I was away?” the doctor asked, pulling away and standing up straight.

“WE WERE REALLY GOOD! HOW DID YOUR SUPER IMPORTANT ADULT MISSION GO, DADDY?” the other child asked. The doctor laughed a relieved, happy laugh.

“Better than I ever dreamed it would go”, he answered.

“who’s that?”

The doctor took the knight by the hand.

“Someone I found along the way. Sans, Papyrus, this is Grillby. My new husband.” The doctor explained.

“Hello”, the knight greeted a little awkwardly.

One of the children furrowed his brow.

“when did you get married?” he asked.

“Recently”, the doctor answered.

The other child’s eyes went wide as realisation hit him.

“SO NOT ONLY ARE WE GOING TO HAVE OUR OLD DADDY BACK, WE’RE GOING TO HAVE _TWO_ DADDIES!?” he gaped.

“If you’ll have me”, the knight said with a smile.

The other child looked him up and down, the grinned.

“sweet. a _brand_ -new dad”, he quipped.

“SAAAAAANS!” the other child groaned as the adults chuckled.

 

 

So the little family went to live in a small home by the edge of the village. The doctor was reunited with his children, the knight eventually opened the tavern he had always wanted, and the two of them had each other.

And they all lived happily ever after.

The End.

**Author's Note:**

> First and foremost, I'd like to file in a formal apology at the insta-marriage. I wanted the final trial to be something I came up with myself, and I was running low on steam after "borrowing" the other trials, so it was either this or a riddle contest.  
> (Also three days is like half a decade in fairy tale time. Like, the whole "What is your name? We shall be married tomorrow!" happened _several times_ in the original Grimm's fairy tales 0_0 )
> 
> The plants used in the fic are actual medical plants! Broadleaf plantain can be used to wounds, stings, and sores in order to facilitate healing and prevent infection, and willow bark contains aspirin (Gaster made some tea out of it off-screen to help with his sword-induced headache). Moon lilies are in fact not an actual plant (you might have noticed that Gaster was, in fact, lying at this point. It serves to be plant savvy!)
> 
> I don't know how single-dad-Gaster managed to reproduce tho. Maybe he got a two-for-one changeling child deal from some fairies?
> 
> I'm still rather new to this writing thing, so feedback would be very much appreciated! Especially since this one was something of a style experiment ^^
> 
>  
> 
> EDIT:  
> [OH MY GOODNESS A FANART EVERYONE GO LOOK](http://lockholmes.tumblr.com/post/172073808075/a-small-fanart-for-the-knight-and-the-doctor)


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